/*
 * Copyright 2012-2020 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.cloud.loadbalancer.annotation;

import java.util.Map;

import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.context.annotation.ImportBeanDefinitionRegistrar;
import org.springframework.core.annotation.AnnotationAttributes;
import org.springframework.core.type.AnnotationMetadata;
import org.springframework.util.StringUtils;

/**
 * @author Dave Syer
 */
public class LoadBalancerClientConfigurationRegistrar
        implements ImportBeanDefinitionRegistrar {

    private static String getClientName(Map<String, Object> client) {
        if (client == null) {
            return null;
        }
        String value = (String) client.get("value");
        if (!StringUtils.hasText(value)) {
            value = (String) client.get("name");
        }
        if (StringUtils.hasText(value)) {
            return value;
        }
        throw new IllegalStateException("Either 'name' or 'value' must be provided in @LoadBalancerClient");
    }

    private static void registerClientConfiguration(BeanDefinitionRegistry registry,
                                                    Object name,
                                                    Object configuration) {
        BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(LoadBalancerClientSpecification.class);
        builder.addConstructorArgValue(name);
        builder.addConstructorArgValue(configuration);
        registry.registerBeanDefinition(name + ".LoadBalancerClientSpecification", builder.getBeanDefinition());
    }

    @Override
    public void registerBeanDefinitions(AnnotationMetadata metadata,
                                        BeanDefinitionRegistry registry) {
        Map<String, Object> attrs = metadata.getAnnotationAttributes(LoadBalancerClients.class.getName());
        if (attrs != null && attrs.containsKey("value")) {
            AnnotationAttributes[] clients = (AnnotationAttributes[]) attrs.get("value");
            for (AnnotationAttributes client : clients) {
                registerClientConfiguration(registry, getClientName(client), client.get("configuration"));
            }
        }
        if (attrs != null && attrs.containsKey("defaultConfiguration")) {
            String name;
            if (metadata.hasEnclosingClass()) {
                name = "default." + metadata.getEnclosingClassName();
            } else {
                name = "default." + metadata.getClassName();
            }
            registerClientConfiguration(registry, name, attrs.get("defaultConfiguration"));
        }
        Map<String, Object> client = metadata.getAnnotationAttributes(LoadBalancerClient.class.getName());
        String name = getClientName(client);
        if (name != null) {
            registerClientConfiguration(registry, name, client.get("configuration"));
        }
    }

}
